“This is a surprise: Overwhelmingly, the people were at home,” Cuomo said. “We thought maybe they were taking public transportation, and we’ve taken special precautions on public transportation, but actually no, because these people were literally at home.”

The “shocking” data came from a survey of more than 100 New York hospitals and about 1,300 new patients, Cuomo said.

It raises the question: “Of the people who are staying home, how rigorously are they staying at home?” Stephen Morse, professor of epidemiology at the Mailman School of Public Health at Columbia University, who focuses on risk assessment of infectious diseases, tells CNBC Make It.

It’s possible that as we enter the ninth and tenth week of fairly extreme prevention measures, people are feeling fatigued or getting too relaxed, says Joseph Vinetz, professor of medicine at the Yale School of Medicine and physician scientist in infectious diseases.

“Just because we’re tired doesn’t mean that the virus cares,” he says. “Viruses have no emotions; they just do their thing.”

According to Cuomo, “much of this comes down to what you do to protect yourself.”

So from masks to groceries, here’s a reminder checklist of the measures epidemiologists and infectious disease experts say you should still absolutely be following, even if you live in a place that’s re-opening:

“There’s a wire that goes over the nose piece that you have to mold to your nose,” Vinetz says. “Then you have to tuck [the mask] under your chin.”

“It’s not hard [to wear a mask], but somebody has to kind of show people how to do it right,” he adds. (This helpful video demonstrates how to wear a mask.) Indeed, wearing a mask can feel somewhat uncomfortable, but both for effective prevention and sanitary reasons, it’s important to keep it on during your entire outing, instead of removing it to take breaks or talk to people.

When you take your mask off, you should remove it without touching the front of it, and wash your hands afterwards, Morse says. “If [masks] become contaminated and you touch them — even if your hands are clean — when you then touch your face afterwards you can infect yourself,” he says.

Steer clear of people on the street

Most of us have heard that we need to be at least six feet from other people when out in public. “That’s not a magic number,” but it’s believed to be the distance necessary to prevent respiratory droplets from reaching you if someone sneezes or coughs, Morse says.

Physical distance can be hard to come by. “There’s a limit to how far you can, especially in New York City, keep apart,” Morse says.

Try to avoid looking at people face-to-face when you’re outside in crowded places, Morse says. “It sounds strange,” but it keeps you out of people’s line of breath, he adds. You can also try to stagger how you’re walking so that you’re side-by-side with others, rather than directly behind someone.

Keep washing your hands diligently

“You always want to make sure your hands are clean,” Morse says. Wash your hands with soap and water or use hand sanitizer at all the normal times, he says.

For example, wash your hands after going to the bathroom; after touching garbage; and before, during and after food prep. “Also after you touch something on the outside and you come back inside,” he says. That includes touching doorknobs, opening packages or pressing elevator buttons.

Wearing gloves may give you a false sense of security, Vinetz says. If you do wear gloves, you should assume that your hands are dirty, and avoid touching your face. “If anybody is wearing gloves, I look at them and say, ‘You’re contaminated, don’t touch anything,'” he says.

Be strategic about running errands

When you’re running essential errands or frequenting businesses as they begin to open, you should still be extra careful.

Take fewer trips to the store to reduce the amount of exposure you have to other people, and order your food and medication for delivery if possible (and don’t accept deliveries in-person), per the CDC. Opt to pay for your items online or over the phone, and use a contactless payment method if you can.

If you do go to the store, stay at least six feet from other people and wear a cloth face covering or mask, the CDC says. Some stores have delineated a “safe distance” on the floor in checkout lines, and wipes available for patrons to disinfect shopping carts. But even still, you should not touch your eyes, nose or mouth throughout the duration of your trip.

Once you’re finished shopping, use hand sanitizer and wash your hands with soap and water when you’re home.

Handle packages and groceries gingerly

When you get a package or bring home a shopping bag, Morse suggests opening it outside of your home. “Leave it outside the door, and then with clean hands, I would lift out the things that were inside,” he says. If the contents look like they need to be cleaned, you can wipe them with a disinfectant, he says, but it’s not totally necessary.

Put the items on a surface that you can clean easily afterwards, and of course wash your hands, Morse says. “There’s only so much you can do, you know, within reason,” he says.

Follow elevator etiquette

Riding the elevator with someone is a comparatively short time to be exposed to their germs, but you should still be mindful. “Minimize the number of people in an elevator,” Morse says. Elevators are slightly less crowded while people are staying home, so you should wait until you can catch a ride alone or with as few people as possible, he says. And wear a face mask while in the elevator, even if you’re riding solo.

Pressing buttons with a key or other inanimate object can’t hurt, but you still need to wash your hands when you come home, he adds.

Keep distance, even while at the park

It’s okay to go to parks or head outdoors for some relief, Vinetz says. “You’re outdoors with air movement, and very little density of people,” he says.

But you should still wear a mask when you’re outside, and stay physically distant from anyone you encounter, he says. If you’re getting together with friends or family outdoors, you must stay at least six feet apart, and be strict about it. Make sure your pals or family members have all been symptom-free for at least 14 days before you meet up.

If that’s not doable, then it’s best to stay home and consider a virtual hangout instead.